// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef IPC_IPC_CHANNEL_HANDLE_H_
#define IPC_IPC_CHANNEL_HANDLE_H_

#include <string>

#include "build/build_config.h"

#if defined(OS_POSIX)
#include "base/file_descriptor_posix.h"
#elif defined(OS_WIN)
#include <windows.h>
#endif // defined (OS_WIN)

// On Windows, any process can create an IPC channel and others can fetch
// it by name.  We pass around the channel names over IPC.
// On Windows the initialization of ChannelHandle with an existing pipe
// handle is provided for convenience.
// NOTE: A ChannelHandle with a pipe handle Will NOT be marshalled over IPC.

// On POSIX, we instead pass around handles to channel endpoints via IPC.
// When it's time to IPC a new channel endpoint around, we send both the
// channel name as well as a base::FileDescriptor, which is itself a special
// type that knows how to copy a socket endpoint over IPC.
//
// In sum, this data structure can be used to pass channel information by name
// in both Windows and Posix. When passing a handle to a channel over IPC,
// use this data structure only for POSIX.

namespace IPC {

struct ChannelHandle {
    // Note that serialization for this object is defined in the ParamTraits
    // template specialization in ipc_message_utils.h.
    ChannelHandle() { }
    // The name that is passed in should be an absolute path for Posix.
    // Otherwise there may be a problem in IPC communication between
    // processes with different working directories.
    ChannelHandle(const std::string& n)
        : name(n)
    {
    }
    ChannelHandle(const char* n)
        : name(n)
    {
    }
#if defined(OS_WIN)
    explicit ChannelHandle(HANDLE h)
        : pipe(h)
    {
    }
#elif defined(OS_POSIX)
    ChannelHandle(const std::string& n, const base::FileDescriptor& s)
        : name(n)
        , socket(s)
    {
    }
#endif // defined(OS_POSIX)

    std::string name;
#if defined(OS_POSIX)
    base::FileDescriptor socket;
#elif defined(OS_WIN)
    // A simple container to automatically initialize pipe handle
    struct PipeHandle {
        PipeHandle()
            : handle(NULL)
        {
        }
        PipeHandle(HANDLE h)
            : handle(h)
        {
        }
        HANDLE handle;
    };
    PipeHandle pipe;
#endif // defined (OS_WIN)
};

} // namespace IPC

#endif // IPC_IPC_CHANNEL_HANDLE_H_
